JP2689916B2 - Active matrix type current control type light emitting element drive circuit - Google Patents
Active matrix type current control type light emitting element drive circuitInfo
- Publication number
- JP2689916B2 JP2689916B2 JP6206078A JP20607894A JP2689916B2 JP 2689916 B2 JP2689916 B2 JP 2689916B2 JP 6206078 A JP6206078 A JP 6206078A JP 20607894 A JP20607894 A JP 20607894A JP 2689916 B2 JP2689916 B2 JP 2689916B2
- Authority
- JP
- Japan
- Prior art keywords
- current
- light emitting
- emitting element
- current control
- transistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000011159 matrix material Substances 0.000 title claims description 11
- 239000010409 thin film Substances 0.000 description 32
- 239000003990 capacitor Substances 0.000 description 14
- 238000010586 diagram Methods 0.000 description 12
- 235000019557 luminance Nutrition 0.000 description 10
- 238000000034 method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 241001270131 Agaricus moelleri Species 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005401 electroluminescence Methods 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ディスプレイに用いら
れる発光素子の駆動装置に関し、特に有機及び無機ＥＬ
（エレクトロルミネンス）、又はＬＥＤ（発光ダイオー
ド）等のような発光輝度が素子を流れる電流により制御
される電流制御型発光素子の駆動回路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a light emitting element used in a display, and more particularly to organic and inorganic EL.
The present invention relates to a drive circuit for a current control type light emitting element such as (electroluminescence) or LED (light emitting diode) whose emission brightness is controlled by a current flowing through the element.
【０００２】[0002]
【従来の技術】有機及び無機ＥＬ、又はＬＥＤ等のよう
な発光素子をアレイ状に組み合わせ、ドットマトリクス
により文字表示を行うディスプレイは、テレビ、携帯端
末等に広く利用されている。2. Description of the Related Art A display in which light emitting elements such as organic and inorganic EL or LEDs are combined in an array to display characters by a dot matrix is widely used in televisions, mobile terminals and the like.
【０００３】特に、自発光素子を用いたこれらのディス
プレイは、液晶を用いたディスプレイと異なり、照明の
ためのバックライトを必要としない、視野角が広い等の
特徴を有し、注目を集めている。In particular, these displays using self-luminous elements are different from the displays using liquid crystals, in that they do not require a backlight for illumination, have a wide viewing angle, etc. There is.
【０００４】中でも、トランジスタ等とこれらの発光素
子とを組み合わせてスタティック駆動を行うアクティブ
マトリクス型と呼ばれるディスプレイは、ダイナミック
駆動を行う単純マトリクス駆動のディスプレイと比較し
て、高輝度、高コントラスト、高精細等の優位性を持っ
ており近年注目されている。Above all, a display called an active matrix type in which a static drive is performed by combining a transistor or the like and these light emitting elements has a higher luminance, a higher contrast and a higher definition than a display in a simple matrix drive which performs a dynamic drive. It has the advantages such as, and has been attracting attention in recent years.
【０００５】この種のディスプレイの従来例として、図
７に、Society for Information Display発行の1990年
秋期大会予稿集『Eurodisplay '90』の第216〜219頁の
発表から引用した、発光素子にＥＬを使用したアクティ
ブマトリクス型ディスプレイの発光素子駆動回路を示
す。As a conventional example of this type of display, FIG. 7 shows an EL element as a light emitting element quoted from the announcement of the 1990 autumn conference proceedings "Eurodisplay '90" published by Society for Information Display on pages 216 to 219. The light emitting element drive circuit of the active matrix type display used is shown.
【０００６】図７を参照して、この駆動回路では、トラ
ンジスタ３５のゲートに接続された走査線３６が選択さ
れて活性化されると、トランジスタ３５がオン状態とな
り、トランジスタ３５に接続されたデータ線３７から信
号がコンデンサ３８に書き込まれる。コンデンサ３８は
トランジスタ４１のゲート・ソース間電圧を決定する。Referring to FIG. 7, in this drive circuit, when the scanning line 36 connected to the gate of the transistor 35 is selected and activated, the transistor 35 is turned on and the data connected to the transistor 35 is turned on. The signal from line 37 is written to capacitor 38. The capacitor 38 determines the gate-source voltage of the transistor 41.
【０００７】そして、走査線３６が非選択となりトラン
ジスタ３５がオフ状態になると、コンデンサ３８の両端
間の電圧は次の周期に走査線３６が選択されるまで保持
される。When the scanning line 36 is deselected and the transistor 35 is turned off, the voltage across the capacitor 38 is held until the scanning line 36 is selected in the next cycle.
【０００８】コンデンサ３８の両端間の電圧に応じて、
電源電極３９→ＥＬ素子４０→トランジスタ４１のドレ
イン−ソース→共通電極４２という経路に沿って電流が
流れ、この電流によりＥＬ素子４０が発光する。Depending on the voltage across capacitor 38,
A current flows along the route of power supply electrode 39 → EL element 40 → drain-source of transistor 41 → common electrode 42, and this current causes EL element 40 to emit light.
【０００９】一般的にコンピュータの端末、パソコンの
モニタ、テレビ等の動画表示を行うためには、各画素の
輝度が変化する階調表示が出来ることが望ましい。Generally, in order to display a moving image on a computer terminal, a personal computer monitor, a television, etc., it is desirable to be capable of gradation display in which the brightness of each pixel changes.
【００１０】図７の駆動回路において階調表示を行うに
は、トランジスタ４１のゲート・ソース電極間に閾値付
近の電圧を印加する必要がある。In order to perform gradation display in the drive circuit of FIG. 7, it is necessary to apply a voltage near the threshold value between the gate and source electrodes of the transistor 41.
【００１１】しかし、トランジスタのゲート電圧・ソー
ス電流特性に、図８に示すようなばらつきがあると、例
えば図７のトランジスタ４１のゲート電極にゲート電圧
ＶＡを印加した場合、トランジスタ４１に流れる電流は
ＩＡ（実線で示す曲線とＶＡとの交点）とＩＢ（破線で
示す曲線とＶＡとの交点）のように異なるため、ＥＬ素
子４０に流れる電流も変わり、本来ならば同じ輝度であ
るはずの領域の輝度が異なり、このため、例えば輝度む
ら等の画質劣化が生じることになる。However, if the gate voltage / source current characteristics of the transistor have variations as shown in FIG. 8, for example, when the gate voltage VA is applied to the gate electrode of the transistor 41 of FIG. Since IA (intersection between the curve shown by the solid line and VA) and IB (intersection between the curve shown by the broken line and VA) are different, the current flowing through the EL element 40 also changes, and the area where the brightness should be the same originally Have different luminances, which causes image quality deterioration such as luminance unevenness.
【００１２】この問題を解決するため、特開平２−１４
８６８７号公報には、素子の閾値付近でのばらつきがあ
っても、この影響を受けずに階調表示を行うＥＬディス
プレイ装置が提案されている。In order to solve this problem, Japanese Patent Laid-Open No. 2-14
Japanese Patent No. 8687 proposes an EL display device that performs gradation display without being affected by variations in the vicinity of the element threshold value.
【００１３】図９を参照して、特開平２−１４８６８７
号公報に提案される回路を説明する。図９は、図７の点
線内の電流制御回路４３に対応する回路部を示してお
り、１６階調表示を行う場合についての例を示すもので
あり、データ線の本数は４本に増加している。Referring to FIG. 9, Japanese Unexamined Patent Publication No. 2-148687
The circuit proposed in the publication will be described. FIG. 9 shows a circuit portion corresponding to the current control circuit 43 in the dotted line of FIG. 7, and shows an example of a case where 16 gradation display is performed, and the number of data lines is increased to four. ing.
【００１４】図９において、４４〜４７は発光素子駆動
用のトランジスタ、４８はカレントミラー回路、４９は
発光素子、５０はトランジスタの各ソース端子及び発光
素子が接続された共通電極の抵抗成分である。トランジ
スタ４４〜４７のドレイン電極は共通接続されてカレン
トミラー回路４８の入力端に接続されている。In FIG. 9, 44 to 47 are transistors for driving a light emitting element, 48 is a current mirror circuit, 49 is a light emitting element, and 50 is a resistance component of a common electrode to which each source terminal of the transistor and the light emitting element are connected. . The drain electrodes of the transistors 44 to 47 are commonly connected and connected to the input terminal of the current mirror circuit 48.
【００１５】図９において、４ビット入力より階調に対
応した組み合わせの信号電圧がトランジスタ４４〜４７
のゲート電圧として印加される。そして、トランジスタ
４４〜４７のうちオン状態のトランジスタに流れる電流
の合計値と同一の電流値がカレントミラー回路４８の出
力端から発光素子４９に供給され、その電流値に応じて
発光素子４９が発光する。In FIG. 9, the signal voltages of the combinations corresponding to the gray scales from the 4-bit input are the transistors 44 to 47.
Is applied as a gate voltage. Then, the same current value as the total value of the currents flowing in the transistors in the ON state among the transistors 44 to 47 is supplied from the output end of the current mirror circuit 48 to the light emitting element 49, and the light emitting element 49 emits light according to the current value. To do.
【００１６】例えばトランジスタ４４〜４７がオン時の
電流値の対数をとった値をそれぞれ倍になるようにすれ
ば（即ち、Ｉ２はＩ１の２倍、Ｉ３はＩ２の２倍（＝Ｉ
１の２2倍）、Ｉ４はＩ３の２倍（＝Ｉ１の２3倍）とす
れば）、トランジスタ４４〜４７のオンする組み合わせ
により１６階調の表示を行うことができる。なお、Ｉ１
〜Ｉ４はトランジスタ４４〜４７がオン状態時のソース
電流をそれぞれ表している。For example, if the values obtained by taking the logarithm of the current value when the transistors 44 to 47 are turned on are each doubled (that is, I2 is twice I1, I3 is twice I2 (= I).
2 twice 1), I4 is if twice the I3 (2 3 times = I1)), can be displayed 16 gradations by a combination of ON of the transistor 44-47. In addition, I1
~ I4 represent source currents when the transistors 44 to 47 are in the ON state, respectively.
【００１７】このときトランジスタを図８のゲート電圧
ＶＢに対応する電流が飽和した領域の電圧で使用するよ
うにすれば、トランジスタの閾値付近での特性がばらつ
いていても、その影響を受けるがことなく、輝度のばら
つきも生じない。At this time, if the transistor is used at a voltage in a region where the current corresponding to the gate voltage VB in FIG. 8 is saturated, even if the characteristic near the threshold value of the transistor varies, it may be affected. There is no variation in brightness.
【００１８】[0018]
【発明が解決しようとする課題】上述の駆動回路におい
て発光素子が最大輝度になった場合、回路にはトランジ
スタ４４〜４７のソース電流Ｉ１〜Ｉ４とカレントミラ
ー回路４８に流れる電流（Ｉ１＋Ｉ２＋Ｉ３＋Ｉ４）の
合計（Ｉ１＋Ｉ２＋Ｉ３＋Ｉ４）×２の電流が流れる。When the light emitting element reaches the maximum brightness in the above-mentioned drive circuit, the total of the source currents I1 to I4 of the transistors 44 to 47 and the current (I1 + I2 + I3 + I4) flowing in the current mirror circuit 48 is included in the circuit. A current of (I1 + I2 + I3 + I4) × 2 flows.
【００１９】この場合、実際に素子の発光に寄与してい
る電流は（Ｉ１＋Ｉ２＋Ｉ３＋Ｉ４）であり、残りの
（Ｉ１＋Ｉ２＋Ｉ３＋Ｉ４）の電流はトランジスタで消
費され、発光には寄与しない。In this case, the current actually contributing to light emission of the device is (I1 + I2 + I3 + I4), and the remaining (I1 + I2 + I3 + I4) current is consumed by the transistor and does not contribute to light emission.
【００２０】近時パソコン、ワークステーション等の端
末では、表示画面の背景を白とし、文字等を黒で表示す
る表示方法が多く用いられているが、このような表示方
法を上記駆動回路で行なう場合、発光に寄与しない消費
電力が増大するという問題が生じる。Recently, in terminals such as personal computers and workstations, a display method in which the background of the display screen is white and the characters and the like are displayed in black is often used. Such a display method is performed by the drive circuit. In this case, there arises a problem that power consumption that does not contribute to light emission increases.
【００２１】更に、トランジスタ４４〜４７と発光素子
４９の端子のうちカレントミラー回路４８に接続されて
いない側の端子が共通に接続される共通電極は抵抗５０
を有するため、電流が流れることにより共通電極におい
て電圧降下が生じる。Further, the common electrode to which the terminals of the transistors 44 to 47 and the light emitting element 49 which are not connected to the current mirror circuit 48 are connected in common is a resistor 50.
Therefore, a voltage drop occurs at the common electrode due to the current flow.
【００２２】この駆動回路において輝度が変化すると、
抵抗５０で生じる電圧降下が変動するため、駆動電圧
は、輝度が低い場合は小さいが、輝度が高い場合には大
きくなるというように、輝度依存性を持つことになる。When the luminance changes in this drive circuit,
Since the voltage drop generated in the resistor 50 fluctuates, the drive voltage has a brightness dependency such that it is small when the brightness is low, but is large when the brightness is high.
【００２３】更に、上記例では、発光素子が１つの場合
について説明を行ったが、複数の駆動回路が接続された
場合には、別の発光素子の輝度によりトランジスタの駆
動電圧が変化するという問題も生じる。Further, in the above example, the case where the number of light emitting elements is one has been described, but when a plurality of driving circuits are connected, the driving voltage of the transistor changes depending on the brightness of another light emitting element. Also occurs.
【００２４】従って、本発明は、前記問題点を解消し、
階調表示を行うアクティブマトリクス型の発光素子の駆
動回路において、最大輝度時に回路に流れる電流を従来
の駆動回路よりも小さくする駆動回路を提供することを
目的とする。更に本発明は、共通電極に流れる最大電流
を従来よりも小さくし、共通電極の抵抗成分により生じ
る電圧降下に伴う駆動回路の上昇を抑える駆動回路を提
供することを目的とする。Therefore, the present invention solves the above problems,
It is an object of the present invention to provide a drive circuit for an active matrix light emitting element that performs gradation display, in which a current flowing through the circuit at maximum brightness is smaller than that of a conventional drive circuit. A further object of the present invention is to provide a drive circuit in which the maximum current flowing through the common electrode is made smaller than in the prior art, and the rise of the drive circuit due to the voltage drop caused by the resistance component of the common electrode is suppressed.
【００２５】[0025]
【課題を解決するための手段】前記目的を達成するた
め、本発明の電流制御型発光素子の駆動回路は、素子に
流れる電流に応じて輝度が変化する発光素子からなる画
素を選択するための走査線と、前記画素を駆動するため
の電圧を供給するデータ線とが基板上にマトリクス状に
配設され、前記走査線と前記データ線との交差部に、前
記発光素子に流れる電流を制御する電流制御トランジス
タと、前記データ線に印加された電圧を前記走査線が選
択時に前記電流制御トランジスタの動作電流を決定する
制御電極に印加するスイッチングトランジスタと、前記
発光素子と、を含むアクティブマトリクス型の電流制御
型発光素子の駆動回路において、前記電流制御トランジ
スタを１又は複数備え、前記発光素子は前記１又は複数
の電流制御トランジスタと互いに電気的に並列形態に接
続され、前記１又は複数の電流制御トランジスタの電流
が流れる電極と前記発光素子の一側の電極との共通接続
点に定電流源を接続して成ることを特徴とするものであ
る。In order to achieve the above object, a drive circuit for a current control type light emitting device of the present invention is for selecting a pixel consisting of a light emitting device whose brightness changes according to a current flowing through the device. Scanning lines and data lines for supplying a voltage for driving the pixels are arranged in a matrix on a substrate, and a current flowing through the light emitting element is controlled at an intersection of the scanning lines and the data lines. An active matrix type including: a current control transistor, a switching transistor that applies a voltage applied to the data line to a control electrode that determines an operating current of the current control transistor when the scanning line is selected, and the light emitting element. Driving circuit for a current control type light emitting device, the current control transistor comprises one or a plurality of the current control transistors, and the light emitting device comprises one or a plurality of current control transistors. And a constant current source connected to a common connection point of an electrode through which a current of the one or more current control transistors flows and an electrode on one side of the light emitting element. It is a feature.
【００２６】また、本発明においては、前記１又は複数
の電流制御トランジスタの電流が流れる他側の電極と前
記発光素子の他側の電極が共通電極に共通接続されてい
ることを特徴としている。前記１又は複数の電流制御ト
ランジスタの電流が流れる他側の電極は、例えば電流制
御トランジスタがｎチャネル型トランジスタの場合、好
ましくはソース電極とされる。The present invention is also characterized in that the electrode on the other side through which the current of the one or more current control transistors flows and the electrode on the other side of the light emitting element are commonly connected to a common electrode. The electrode on the other side through which the current of the one or more current control transistors flows is preferably a source electrode when the current control transistor is an n-channel transistor, for example.
【００２７】さらに、本発明においては、前記１又は複
数の電流制御トランジスタに流れるオン電流の合計が前
記定電流源が供給する定電流値に略等しいか又はそれ以
上とされ、前記１又は複数の電流制御トランジスタが全
てオン状態時に前記発光素子が発光しないように制御さ
れることを特徴とする。Furthermore, in the present invention, the total of the on-currents flowing through the one or more current control transistors is substantially equal to or more than the constant current value supplied by the constant current source, and the one or more current control transistors are provided. The current control transistors are controlled so that the light emitting element does not emit light when all the current control transistors are in an ON state.
【００２８】そして、本発明においては、好ましくは、
前記データ線の信号電圧に、共通電極の抵抗成分に定電
流源の一定電流値を乗じて成る電圧が直流バイアス電圧
として印加される。In the present invention, preferably,
A voltage obtained by multiplying the signal voltage of the data line by the resistance component of the common electrode by a constant current value of the constant current source is applied as a DC bias voltage.
【００２９】さらにまた、本発明は、前記電流制御型発
光素子の駆動回路を複数個用いた発光素子アレイであっ
て、前記電流制御型発光素子の電流を決定する前記電流
制御トランジスタのソース電極が共通に接続されている
ことを特徴とする電流制御型発光素子アレイを提供す
る。Furthermore, the present invention is a light emitting element array using a plurality of drive circuits for the current control type light emitting element, wherein the source electrode of the current control transistor for determining the current of the current control type light emitting element is Provided is a current control type light emitting element array, which is connected in common.
【００３０】[0030]
【作用】上記構成のもと、本発明によれば、発光素子が
最大輝度時には、従来例のように電流制御トランジスタ
には電流が流れず、発光素子にのみ電流が流れるように
構成されているため、回路の消費電力を低減化すること
が出来る。例えば本発明に係る回路を用いてアレイを構
成し、表示画面において白背景に黒の文字という様な表
示を行った場合、アレイでの消費電力を従来よりも大幅
に低減することが出来る。According to the present invention having the above structure, when the light emitting element has the maximum luminance, no current flows through the current control transistor as in the conventional example, but only the light emitting element flows. Therefore, power consumption of the circuit can be reduced. For example, when an array is formed by using the circuit according to the present invention and a display such as black characters on a white background is displayed on the display screen, the power consumption of the array can be significantly reduced as compared with the conventional case.
【００３１】更に、本発明によれば、共通電極に流れる
最大電流を従来例よりも小さくすることが出来るため、
共通電極の抵抗成分により生じる電圧降下に伴う駆動電
圧の上昇を抑えることが出来る。そして、本発明によれ
ば、共通電極での電圧降下は表示によらず一定とされる
ため、駆動電圧を容易に補正することができる。Further, according to the present invention, the maximum current flowing through the common electrode can be made smaller than that of the conventional example,
It is possible to suppress an increase in driving voltage due to a voltage drop caused by the resistance component of the common electrode. Further, according to the present invention, the voltage drop at the common electrode is constant regardless of the display, so that the drive voltage can be easily corrected.
【００３２】[0032]
【実施例】図面を参照して、本発明の実施例を以下に説
明する。Embodiments of the present invention will be described below with reference to the drawings.
【００３３】[0033]
【実施例１】図１は本発明の第１の実施例の回路図であ
り、発光素子として電荷注入型の有機薄膜ＥＬ素子（以
下「有機薄膜ＥＬ素子」と略記する）を用いた場合のも
のである。[Embodiment 1] FIG. 1 is a circuit diagram of a first embodiment of the present invention, in which a charge injection type organic thin film EL element (hereinafter abbreviated as "organic thin film EL element") is used as a light emitting element. It is a thing.
【００３４】図１において、１は発光素子である有機薄
膜ＥＬ素子、２は有機薄膜ＥＬ素子１に流れる電流を制
御するトランジスタ、３は有機薄膜ＥＬ素子１及びトラ
ンジスタ２に流れる電流として一定電流を供給する定電
流回路（「定電流源」ともいう）、４はトランジスタ２
のゲート・ソース間電圧を決定するコンデンサ、５はコ
ンデンサ４に信号電圧を供給するスイッチングトランジ
スタ、６はスイッチングトランジスタ５を選択する走査
信号を供給する走査線、７は走査線６がオンとされ選択
されたスイッチングトランジスタ５を介してコンデンサ
４に電荷を供給するデータ線、８は有機薄膜ＥＬ素子１
に電流を供給する電源電極、９はデータ線７との間の電
位差でトランジスタの動作点を決定する共通電極であ
る。In FIG. 1, 1 is an organic thin film EL element which is a light emitting element, 2 is a transistor for controlling a current flowing through the organic thin film EL element 1, 3 is a constant current as a current flowing through the organic thin film EL element 1 and the transistor 2. Constant current circuit (also referred to as "constant current source") 4 for supplying is a transistor 2
, 5 is a switching transistor that supplies a signal voltage to the capacitor 4, 6 is a scanning line that supplies a scanning signal that selects the switching transistor 5, and 7 is a scanning line 6 that is turned on and selected. Data line for supplying electric charge to the capacitor 4 via the switched switching transistor 5, and 8 is the organic thin film EL element 1.
Is a power supply electrode for supplying a current to the data line, and 9 is a common electrode which determines the operating point of the transistor by the potential difference between the data line and the data line.
【００３５】ここで、トランジスタ２のゲート電圧とソ
ース電流の関係が図２に示すようなものとされ、また、
有機薄膜ＥＬ素子１に流れる電流密度と輝度の関係が図
３に示すような関係にあるものとする。なお、図２にお
いて、縦軸のソース電流の目盛り（単位はｍＡ）は対数
表示とされ、数値１Ｅ−３、１Ｅ−５等はそれぞれ１×
１０-3、１×１０-5を表わす。Here, the relationship between the gate voltage and the source current of the transistor 2 is as shown in FIG.
It is assumed that the relationship between the density of the current flowing in the organic thin film EL element 1 and the brightness has the relationship shown in FIG. In FIG. 2, the scale (unit: mA) of the source current on the vertical axis is logarithmic, and the numerical values 1E-3, 1E-5, etc. are 1 ×, respectively.
It represents 10 −3 and 1 × 10 −5 .
【００３６】また、以下では、本実施例として、有機薄
膜ＥＬ素子１を、画素数が横６４０ドット、縦４８０ド
ットの対角サイズが２４ｃｍのノートパソコン用のディ
スプレイに使用する例について説明する。In the following, as the present embodiment, an example in which the organic thin film EL element 1 is used for a display for a notebook computer having a pixel size of 640 dots in the horizontal direction and 480 dots in the vertical direction and a diagonal size of 24 cm will be described.
【００３７】この場合、有機薄膜ＥＬ素子１の画素のサ
イズは３００μｍ×３００μｍである。In this case, the pixel size of the organic thin film EL element 1 is 300 μm × 300 μm.
【００３８】ディスプレイに使用した場合の有機薄膜Ｅ
Ｌ素子１の発光輝度は、およそ１００（ｃｄ／ｍ2）必
要とされるため、図３より、有機薄膜ＥＬ素子１に流れ
る電流は最大で約１×１０-3（ｍＡ）であることがわか
る。Organic thin film E when used for display
Since the light emission luminance of the L element 1 is required to be about 100 (cd / m 2 ), it can be seen from FIG. 3 that the maximum current flowing through the organic thin film EL element 1 is about 1 × 10 −3 (mA). Recognize.
【００３９】上記条件を前提として、まず図１の定電流
回路３に流れる電流を１×１０-3（ｍＡ）に設定する。Under the above conditions, first, the current flowing through the constant current circuit 3 of FIG. 1 is set to 1 × 10 −3 (mA).
【００４０】次に、本実施例に係る駆動回路の動作につ
いて説明する。Next, the operation of the drive circuit according to this embodiment will be described.
【００４１】まず、トランジスタ２のゲート電圧が０
（Ｖ）の場合、図２を参照してトランジスタ２に流れる
電流はほぼ０とみなせるため、定電流回路３の電流は全
て有機薄膜ＥＬ素子１に流れる。First, the gate voltage of the transistor 2 is 0
In the case of (V), since the current flowing through the transistor 2 can be regarded as almost 0 with reference to FIG. 2, all the current of the constant current circuit 3 flows through the organic thin film EL element 1.
【００４２】このとき、図３を参照して、有機薄膜ＥＬ
素子１の輝度は約８０（ｃｄ／ｍ2）となる。At this time, referring to FIG. 3, the organic thin film EL
The brightness of the element 1 is about 80 (cd / m 2 ).
【００４３】次に、トランジスタ２のゲート電圧が５
（Ｖ）のときは、図２を参照してトランジスタ２には約
２×１０-3（ｍＡ）の電流が流れることになるが、定電
流回路３が接続されているため、トランジスタ２には１
×１０-3（ｍＡ）の電流が流れる。このため、有機薄膜
ＥＬ素子１には電流が流れなくなるため、発光は停止す
る。Next, the gate voltage of the transistor 2 is 5
At (V), referring to FIG. 2, a current of about 2 × 10 −3 (mA) flows in the transistor 2, but since the constant current circuit 3 is connected, the transistor 2 does not 1
A current of × 10 -3 (mA) flows. Therefore, no current flows in the organic thin film EL element 1, and the light emission stops.
【００４４】そして、トランジスタ２のゲート電圧を５
（Ｖ）から０（Ｖ）の間に設定することにより、有機薄
膜ＥＬ素子１の輝度をトランジスタ２のゲート電圧値に
応じて変化させることができる。Then, the gate voltage of the transistor 2 is set to 5
By setting between (V) and 0 (V), the luminance of the organic thin film EL element 1 can be changed according to the gate voltage value of the transistor 2.
【００４５】図４は、本実施例について、共通電極９に
抵抗１１が存在する場合の回路図を示している。なお、
図４の回路図は、図１の一点鎖線で示された電流制御回
路１０に相当する回路構成を示しており、以下では図１
との相違点のみを説明する。FIG. 4 shows a circuit diagram of this embodiment when the common electrode 9 has a resistor 11. In addition,
The circuit diagram of FIG. 4 shows a circuit configuration corresponding to the current control circuit 10 shown by the alternate long and short dash line of FIG.
Only the differences from
【００４６】図４において、抵抗１１に流れる電流は、
トランジスタ２のオン／オフ状態の如何に拘らず常に定
電流回路３に流れる電流に等しい。In FIG. 4, the current flowing through the resistor 11 is
It is always equal to the current flowing through the constant current circuit 3 regardless of the on / off state of the transistor 2.
【００４７】よって、定電流回路３に流れる電流をＩ
（Ａ）、抵抗１１の値をＲ（Ω）とすると、トランジス
タ２のソース電圧は、常に図１のソース電圧よりもＩ×
Ｒ（Ｖ）だけ高くなっているため、予めデータ線７の電
圧にＩ×Ｒ（Ｖ）の直流バイアス電圧を印加することに
より、図１の場合と全く同一の電圧・輝度特性を得るこ
とが可能である。Therefore, the current flowing through the constant current circuit 3 is I
(A), assuming that the value of the resistor 11 is R (Ω), the source voltage of the transistor 2 is always I × more than the source voltage of FIG.
Since it is increased by R (V), it is possible to obtain exactly the same voltage / luminance characteristics as in the case of FIG. 1 by applying a DC bias voltage of I × R (V) to the voltage of the data line 7 in advance. It is possible.
【００４８】図５は、本実施例において、トランジスタ
２を複数設けて階調表示を行う場合の回路の１例であ
る。FIG. 5 shows an example of a circuit in the case where a plurality of transistors 2 are provided for gradation display in this embodiment.
【００４９】電流制御用トランジスタ１７は、第１のデ
ータ線１２、トランジスタ１５、コンデンサ１９により
駆動される。またトランジスタ１６は、第２のデータ線
１３、トランジスタ１４、コンデンサ１８により駆動さ
れる。また、図面の簡略化のため定電流回路３はその内
部回路を示さずに、定電流源を指示する回路記号（シン
ボル）で表わしている。個々のトランジスタ１６及び１
７の駆動方法は、図１を参照して説明したものと同様で
ある。The current controlling transistor 17 is driven by the first data line 12, the transistor 15 and the capacitor 19. The transistor 16 is driven by the second data line 13, the transistor 14, and the capacitor 18. Further, for simplification of the drawing, the constant current circuit 3 is represented by a circuit symbol (symbol) indicating a constant current source without showing its internal circuit. Individual transistors 16 and 1
The driving method of 7 is the same as that described with reference to FIG.
【００５０】本実施例では、トランジスタ１６及び１７
は共に、オン状態時にドレイン−ソース間に流れる電流
（即ち、オン電流）が約２×１０-3（ｍＡ）とされ、且
つゲート電圧とソース電流の関係が図２に示す特性を有
するものとし、また、定電流回路３の電流は４×１０-3
（ｍＡ）と一定である場合について説明する。In this embodiment, the transistors 16 and 17 are used.
In both cases, the current flowing between the drain and the source in the ON state (that is, the ON current) is about 2 × 10 −3 (mA), and the relationship between the gate voltage and the source current has the characteristics shown in FIG. , And the current of the constant current circuit 3 is 4 × 10 −3
The case where it is constant at (mA) will be described.
【００５１】第１のデータ線１２、第２のデータ線１３
が共に０（Ｖ）の場合、トランジスタ１６及び１７に流
れる電流はほぼ０とみなせるので、図３より、有機薄膜
ＥＬ素子１の輝度は約２００（ｃｄ／ｍ2）になる。First data line 12 and second data line 13
When both are 0 (V), the current flowing in the transistors 16 and 17 can be regarded as almost 0, and therefore the luminance of the organic thin film EL element 1 is about 200 (cd / m 2 ) from FIG.
【００５２】どちらか一方のデータ線が５（Ｖ）になっ
た場合、例えば第１のデータ線１２のみが５（Ｖ）にな
ったとすると、トランジスタ１７には約２×１０-3（ｍ
Ａ）の電流が流れるため、有機薄膜ＥＬ素子１には２×
１０-3（ｍＡ）の電流が流れ、輝度は１００（ｃｄ／ｍ
2）になる。When either one of the data lines has a voltage of 5 (V), for example, if only the first data line 12 has a voltage of 5 (V), the transistor 17 has about 2 × 10 -3 (m).
Since the current of A) flows, the organic thin film EL element 1 has 2 ×
A current of 10 -3 (mA) flows and the brightness is 100 (cd / m
2 ).
【００５３】データ線１２及び１３が共に５（Ｖ）にな
った場合、トランジスタ１６と１７には、合計４×１０
-3（ｍＡ）の電流が流れ、有機薄膜ＥＬ素子１には電流
は流れないため、有機薄膜ＥＬ素子１は発光しない。When both the data lines 12 and 13 have a voltage of 5 (V), the transistors 16 and 17 have a total of 4 × 10.
Since a current of -3 (mA) flows and no current flows in the organic thin film EL element 1, the organic thin film EL element 1 does not emit light.
【００５４】このように、トランジスタ１６及び１７の
オン／オフ状態の組み合わせを変えることにより、有機
薄膜ＥＬ素子１を用いて階調表示を行うことが可能とな
る。By changing the combination of the on / off states of the transistors 16 and 17 as described above, it is possible to perform gradation display using the organic thin film EL element 1.
【００５５】なお、本実施例においては、トランジスタ
１６及び１７のオン電流は互いに同一として説明を行っ
たが、本発明はこれに限らず、トランジスタ１６と１７
のオン電流の値を変えておけば、トランジスタが両方と
もオンしている場合、トランジスタが両方ともオフして
いる場合、トランジスタ１６のみがオンしている場合、
トランジスタ１７のみがオンしている場合、の４通りの
階調を得ることができる。Although the ON currents of the transistors 16 and 17 are the same in this embodiment, the present invention is not limited to this, and the transistors 16 and 17 are not limited to this.
If the value of the on-current of is changed, when both transistors are on, when both transistors are off, when only the transistor 16 is on,
When only the transistor 17 is turned on, four gradations can be obtained.
【００５６】本実施例では発光素子として有機薄膜ＥＬ
素子１を用いたが、本発明はこれに限らず、電流値によ
り輝度が決定する例えば無機ＥＬ、ＬＥＤのような発光
素子を用いても同様の回路を構成できる。In this embodiment, an organic thin film EL is used as a light emitting element.
Although the element 1 is used, the present invention is not limited to this, and a similar circuit can be configured by using a light emitting element such as an inorganic EL or LED whose brightness is determined by a current value.
【００５７】また、本実施例ではトランジスタ２がｎチ
ャネルのＦＥＴの場合を示したが、本発明はこれに限ら
ずｐチャネルのＦＥＴ、バイポーラのトランジスタ等を
使用しても同様の動作を行う回路を構成できることは明
白である。Further, although the case where the transistor 2 is an n-channel FET is shown in the present embodiment, the present invention is not limited to this, and a circuit which performs the same operation even if a p-channel FET, a bipolar transistor or the like is used. It is clear that can be configured.
【００５８】更に、定電流回路３もｐチャネルのＦＥＴ
で構成した例を挙げたが、本発明を実施する場合の構成
はこれに限らない。Further, the constant current circuit 3 is also a p-channel FET.
However, the configuration when the present invention is implemented is not limited to this.
【００５９】また、本実施例においてはトランジスタ２
が２つの場合について述べたが、本発明はこれに限らず
２つ以上のトランジスタを用いて更に階調数を増やした
場合についても同様である。またトランジスタ２のオン
電流が同一である場合について説明したが、オン電流を
変えて輝度を可変できるようにした場合も同様である。Further, in this embodiment, the transistor 2
However, the present invention is not limited to this, and the same applies to the case where the number of gradations is further increased by using two or more transistors. Although the case where the on-currents of the transistors 2 are the same has been described, the same applies to the case where the on-current is changed so that the luminance can be changed.
【００６０】[0060]
【実施例２】次に、本発明の第２の実施例を説明する。
図６は本発明の第２の実施例を示しており、前記実施例
の駆動回路を用いて電流制御型発光素子に有機薄膜ＥＬ
素子を使用したマトリクスアレイを作成した場合の等価
回路を、説明のために２画素として示した回路である。Embodiment 2 Next, a second embodiment of the present invention will be described.
FIG. 6 shows a second embodiment of the present invention, in which an organic thin film EL is used as a current control type light emitting device by using the drive circuit of the above embodiment.
An equivalent circuit in the case of forming a matrix array using elements is a circuit shown as two pixels for the sake of explanation.
【００６１】図６において、２０及び２１は有機薄膜Ｅ
Ｌ素子、２２及び２３は有機薄膜ＥＬ素子の電流制御用
のトランジスタ、２４及び２５は定電流回路、２６及び
２７はコンデンサ、２８及び２９はスイッチングトラン
ジスタ、３０及び３１は走査線、３２はデータ線、３３
は共通電極、３４は共通電極の抵抗成分である。In FIG. 6, 20 and 21 are organic thin films E.
L elements, 22 and 23 are transistors for current control of organic thin film EL elements, 24 and 25 are constant current circuits, 26 and 27 are capacitors, 28 and 29 are switching transistors, 30 and 31 are scanning lines, and 32 is a data line. , 33
Is a common electrode, and 34 is a resistance component of the common electrode.
【００６２】いま、定電流回路２４及び２５の電流値が
どちらもＩ（Ａ）であるとすると、抵抗３４に流れる電
流は、有機薄膜ＥＬ素子２０及び２１に流れる電流の如
何に拘らず常に２×Ｉ（Ａ）となり一定である。If the current values of the constant current circuits 24 and 25 are both I (A), the current flowing through the resistor 34 is always 2 regardless of the current flowing through the organic thin film EL elements 20 and 21. It becomes × I (A) and is constant.
【００６３】このとき、抵抗３４の値をＲ（Ω）とする
と、抵抗３４における電圧降下は２×Ｉ×Ｒ（Ｖ）で一
定となり、有機薄膜ＥＬ素子２０及び２１に流れる電流
により抵抗３４での電圧降下の大きさが変わることは無
い。At this time, assuming that the value of the resistor 34 is R (Ω), the voltage drop in the resistor 34 is constant at 2 × I × R (V), and the resistor 34 is caused by the current flowing through the organic thin film EL elements 20 and 21. The magnitude of the voltage drop on the will not change.
【００６４】このことは、共通電極３３の電位が有機薄
膜ＥＬ素子２０及び２１の電流の如何によらず常に一定
であることを示しており、データ線３２に印加するトラ
ンジスタ２２及び２３の電圧に２×Ｉ×Ｒ（Ｖ）分の直
流バイアス電圧を印加しておけば、例えば有機薄膜ＥＬ
素子２０または２１に流れる電流が変化しても、トラン
ジスタ２２と２３のソース電圧は変化しないため、他の
素子の影響を受けること無く輝度制御することが可能で
ある。This indicates that the potential of the common electrode 33 is always constant regardless of the current of the organic thin film EL elements 20 and 21, and the voltage of the transistors 22 and 23 applied to the data line 32 is the same. If a DC bias voltage of 2 × I × R (V) is applied, for example, an organic thin film EL
Even if the current flowing through the element 20 or 21 changes, the source voltages of the transistors 22 and 23 do not change, so that the brightness can be controlled without being affected by other elements.
【００６５】本実施例では、説明の簡単のために、発光
素子の駆動回路が２つ並んだ最も簡単な場合についての
説明を行ったが、本発明は２つ以上の発光素子の駆動回
路がアレイ化されていても同様の効果を得ることができ
る。In this embodiment, for the sake of simplicity of description, the simplest case where two driving circuits for light emitting elements are arranged has been described. However, the present invention has a driving circuit for two or more light emitting elements. The same effect can be obtained even when arrayed.
【００６６】また、本実施例においては各有機薄膜ＥＬ
素子に接続されたトランジスタが１つの場合について説
明したが、前記第１の実施例で説明したように、１つの
発光素子を複数のトランジスタで駆動する場合でも同様
の効果を得ることができることは明白である。Further, in the present embodiment, each organic thin film EL
Although the case where one transistor is connected to the element has been described, it is apparent that the same effect can be obtained even when one light emitting element is driven by a plurality of transistors as described in the first embodiment. Is.
【００６７】[0067]
【発明の効果】以上説明したように本発明によれば、発
光素子の最大輝度時において回路に流れる電流は、定電
流源から発光素子に流れる電流のみに制御され、電流制
御トランジスタにも発光素子に流れる電流と同一のオン
電流を流す構成とされた従来例と比較して、回路の消費
電流を大幅に低減することができる。As described above, according to the present invention, the current flowing through the circuit at the maximum brightness of the light emitting element is controlled only by the current flowing from the constant current source to the light emitting element, and the current control transistor also has the light emitting element. It is possible to significantly reduce the current consumption of the circuit as compared with the conventional example in which the same on-current as the current flowing through the circuit is made to flow.
【００６８】また、本発明によれば、回路の消費電力を
抑えることが出来るため、例えば本発明に係る回路を用
いてアレイを構成し、表示画面において白背景に黒の文
字というような表示を行った場合、アレイにおける消費
電力を従来よりも大幅に削減することが出来る。Further, according to the present invention, since the power consumption of the circuit can be suppressed, for example, an array is formed by using the circuit according to the present invention, and a display such as black characters on a white background is displayed on the display screen. If this is done, the power consumption of the array can be reduced significantly compared to the past.
【００６９】更に、本発明によれば、共通電極に流れる
最大電流を従来例よりも小さくすることが出来るため、
共通電極の抵抗成分により生じる電圧降下に伴う駆動電
圧の上昇を抑えることが出来る。Further, according to the present invention, the maximum current flowing through the common electrode can be made smaller than that in the conventional example,
It is possible to suppress an increase in driving voltage due to a voltage drop caused by the resistance component of the common electrode.
【００７０】そして、本発明によれば、共通電極におけ
る電圧降下は、表示によらず常に一定とされるため、駆
動電圧の補正が容易化される。Further, according to the present invention, the voltage drop at the common electrode is always constant regardless of the display, so that the correction of the drive voltage is facilitated.
【図１】本発明の第１の実施例の構成を示す回路図であ
る。FIG. 1 is a circuit diagram showing a configuration of a first exemplary embodiment of the present invention.
【図２】トランジスタのゲート電圧・ドレイン電流特性
の１例を示す図である。FIG. 2 is a diagram showing an example of gate voltage / drain current characteristics of a transistor.
【図３】有機薄膜ＥＬ素子の電流輝度特性を示す図であ
る。FIG. 3 is a diagram showing current-luminance characteristics of an organic thin film EL element.
【図４】本発明の第１の実施例を説明する第２の回路図
である。FIG. 4 is a second circuit diagram illustrating the first embodiment of the present invention.
【図５】本発明の第１の実施例を説明する第３の回路図
である。FIG. 5 is a third circuit diagram illustrating the first embodiment of the present invention.
【図６】本発明の第２の実施例を説明する回路図であ
る。FIG. 6 is a circuit diagram illustrating a second embodiment of the present invention.
【図７】従来の発光素子の駆動回路を示す図である。FIG. 7 is a diagram showing a conventional drive circuit for a light emitting element.
【図８】トランジスタ特性のばらつきを示す特性図であ
る。FIG. 8 is a characteristic diagram showing variations in transistor characteristics.
【図９】トランジスタのばらつきを抑制する従来例の回
路図である。FIG. 9 is a circuit diagram of a conventional example that suppresses variations in transistors.
１ 有機薄膜ＥＬ素子 ２ トランジスタ ３ 定電流回路 ４ コンデンサ ５ トランジスタ ６ 走査線 ７ データ線 ８ 電源電極 ９ 共通電極 １０ 電流制御回路 １１ 抵抗 １２ 第１のデータ線 １３ 第２のデータ線 １４〜１７ トランジスタ １８、１９ コンデンサ ２０、２１ 有機薄膜ＥＬ素子 ２２、２３ トランジスタ ２４、２５ 定電流源 ２６、２７ コンデンサ ２８、２９ コンデンサ ３０、３１ 走査線 ３２ データ線 ３３ 共通電極 ３４ 抵抗 ３５ トランジスタ ３６ 走査線 ３７ データ線 ３８ コンデンサ ３９ 電源電極 ４０ ＥＬ素子 ４１ トランジスタ ４２ 共通電極 ４３ 電流制御回路 ４４〜４７ トランジスタ ４８ カレントミラー回路 ４９ 発光素子 ５０ 抵抗 1 Organic Thin Film EL Element 2 Transistor 3 Constant Current Circuit 4 Capacitor 5 Transistor 6 Scan Line 7 Data Line 8 Power Supply Electrode 9 Common Electrode 10 Current Control Circuit 11 Resistor 12 First Data Line 13 Second Data Line 14-17 Transistor 18 , 19 capacitor 20, 21 organic thin film EL element 22, 23 transistor 24, 25 constant current source 26, 27 capacitor 28, 29 capacitor 30, 31 scanning line 32 data line 33 common electrode 34 resistance 35 transistor 36 scanning line 37 data line 38 Capacitor 39 Power supply electrode 40 EL element 41 Transistor 42 Common electrode 43 Current control circuit 44 to 47 Transistor 48 Current mirror circuit 49 Light emitting element 50 Resistance
Claims (5)
発光素子からなる画素を選択するための走査線と、前記
画素を駆動するための電圧を供給するデータ線とが基板
上にマトリクス状に配設され、前記走査線と前記データ
線との交差部に、前記発光素子に流れる電流を制御する
電流制御トランジスタと、前記データ線に印加された電
圧を前記走査線が選択時に前記電流制御トランジスタの
動作電流を決定する制御電極に印加するスイッチングト
ランジスタと、前記発光素子と、を含むアクティブマト
リクス型の電流制御型発光素子の駆動回路において、 前記電流制御トランジスタを１又は複数備え、前記発光
素子は前記１又は複数の電流制御トランジスタと互いに
電気的に並列形態に接続され、前記１又は複数の電流制
御トランジスタの電流が流れる電極と前記発光素子の一
側の電極との共通接続点に定電流源を接続して成ること
を特徴とする電流制御型発光素子の駆動回路。1. A matrix of scan lines for selecting a pixel formed of a light emitting element, the brightness of which changes according to a current flowing through the element, and a data line for supplying a voltage for driving the pixel. And a current control transistor for controlling a current flowing through the light emitting element at an intersection of the scanning line and the data line, and a current control transistor when the scanning line selects a voltage applied to the data line. A drive circuit for an active matrix current-controlled light-emitting element, comprising: a switching transistor applied to a control electrode that determines an operating current of the transistor; and the light-emitting element, wherein the current-controlled transistor is one or more. Is electrically connected to the one or more current control transistors in parallel with each other, and is electrically connected to the one or more current control transistors. A drive circuit for a current control type light emitting device, characterized in that a constant current source is connected to a common connection point of an electrode through which a current flows and an electrode on one side of the light emitting device.
電流が流れる他側の電極と前記発光素子の他側の電極が
共通電極に共通接続されていることを特徴とする請求項
１記載の電流制御型発光素子の駆動回路。2. The current according to claim 1, wherein the electrode on the other side through which the current of the one or more current control transistors flows and the electrode on the other side of the light emitting element are commonly connected to a common electrode. Control type light emitting element drive circuit.
流れるオン電流の合計が前記定電流源が供給する定電流
値に略等しいか又はそれ以上とされ、前記１又は複数の
電流制御トランジスタが全てオン状態時に前記発光素子
が発光しないように制御されることを特徴とする請求項
１記載の電流制御型発光素子の駆動回路。3. A total of on-currents flowing through the one or more current control transistors is substantially equal to or more than a constant current value supplied by the constant current source, and all of the one or more current control transistors are provided. 2. The drive circuit for a current control type light emitting element according to claim 1, wherein the light emitting element is controlled so as not to emit light in an ON state.
抗成分に定電流源の一定電流値を乗じて成る電圧を直流
バイアス電圧として印加することを特徴とする請求項２
記載の電流制御型発光素子の駆動回路。4. A DC bias voltage is applied to the signal voltage of the data line, which is obtained by multiplying the resistance component of the common electrode by a constant current value of a constant current source.
A current control type light emitting element drive circuit.
駆動回路を複数個用いた発光素子アレイであって、前記
電流制御型発光素子の電流を決定する前記電流制御トラ
ンジスタのソース電極が共通に接続されていることを特
徴とする電流制御型発光素子アレイ。5. A light emitting element array using a plurality of drive circuits for the current control type light emitting element according to claim 1, wherein a source electrode of the current control transistor for determining a current of the current control type light emitting element. A current control type light emitting element array, which is connected in common.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6206078A JP2689916B2 (en) | 1994-08-09 | 1994-08-09 | Active matrix type current control type light emitting element drive circuit |
| US08/512,643 US5714968A (en) | 1994-08-09 | 1995-08-08 | Current-dependent light-emitting element drive circuit for use in active matrix display device |
| US08/941,026 US5940053A (en) | 1994-08-09 | 1997-09-30 | Current-dependent light-emitting element drive circuit for use in active matrix display device |
| US09/291,978 US6011529A (en) | 1994-08-09 | 1999-04-15 | Current-dependent light-emitting element drive circuit for use in active matrix display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6206078A JP2689916B2 (en) | 1994-08-09 | 1994-08-09 | Active matrix type current control type light emitting element drive circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0854835A JPH0854835A (en) | 1996-02-27 |
| JP2689916B2 true JP2689916B2 (en) | 1997-12-10 |
Family
ID=16517467
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6206078A Expired - Fee Related JP2689916B2 (en) | 1994-08-09 | 1994-08-09 | Active matrix type current control type light emitting element drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2689916B2 (en) |
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